Oxidative stress and beta cell dysfunction

Autoimmune Type 1 A Diabetes (T1D) is characterized by dependence on exogenous insulin consequential to the autoimmune attack and destruction of insulin-producing islet beta cells. Pancreatic islet cell inflammation, or insulitis, precedes beta cell death and T1D onset. In the insulitic lesion, innate immune cells produce chemokines and cytokines that recruit and activate adaptive immune cells (Eizirik D et al., Nat Rev Endocrinol 5:219-226, 2009). Locally produced cytokines not only increase immune surveillance of beta cells (Hanafusa T and Imagawa A, Ann NY Acad Sci 1150:297-299, 2008), but also cause beta cell dysfunction and decreased insulin secretion due to the generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) by the beta cells. This, coupled to the high levels of ROS and RNS secreted by activated macrophages and the low antioxidant capacities of beta cells (Huurman VA, PLoS One 3:e2435, 2008; Schatz D, Pediatr Diabetes 5:72-79, 2004; Verge CF, Diabetes 44:1176-1179, 1995), implicates free radicals as important effectors in T1D pathogenesis (Eizirik D et al., Nat Rev Endocrinol 5:219-226, 2009; Hanafusa T and Imagawa A, Ann NY Acad Sci 1150:297-299, 2008; Eisenbarth GS and Jeffrey J, Arq Bras Endocrinol Metabol 52:146-155, 2008; Pietropaolo M et al., Pediatr Diabetes 6:184-192, 2005).